1. The Evolution of Living Things
Changes over time

2. Differences Among Organisms
Variations: any difference between individuals of the same species
Caused by
inherited traits
mutations
What is a species?

3. Variations Can be helpful, harmful, or have no impact
Helpful variations (adaptations) accumulate in a population
Eventually a new species forms with the new variation
This process is evolution
Process in which inherited characteristics within
a population change over generations such that
new species sometimes arise
What is an adaptation?

4. Species
a group of organisms that can mate and produce fertile offspring

5. Speciation Formation of a new species
Separation—part of population becomes separated from rest
Adaptations—both populations undergo natural selection. If environments are different, adaptations will also differ
Division—over many generations separate populations become different species

6. Do species change over time?
Evidence suggest they have
Many organisms have appeared and died out
What is extinction?

7. Evidence of changes over time
Fossils and the fossil record
DNA
Comparative structures
Embryology

8. Evidence of evolution: Fossils and Fossil Record
Show estimated age and physical
similarities of organisms
Show changes from earlier life forms

9. Pangea and the fossil record

10. Pangea and the fossil record

11. Evidence of Evolution: DNA
Many organisms share common DNA
The more DNA that is shared, the more
closely related the two organisms are

12. Evidence of Evolution: comparative structures
Homologous Structures
same structures
Analogous structures
Different structures with similar function
Vestigial structures
remnants that were important but are no longer needed
Bird

13. Homologous structures

14. Analogous structures

15. Vestigial structures Eyes of cave dwelling fish and mole rats
Leg and hip bones in whales
Teeth that quickly disappear in duck billed platypus
Wings on flightless birds

16. Evidence of Evolution: Embryological Development

17. Evidence of Evolution: Embryological Development

18. Evidence of Evolution: Common Ancestry

19. Common ancestors in canines

20. Evidence from Whales

21. Horse Evolution

22. Evolution took a long time

23. Cladograms
Charts that show common ancestors among organisms

24. Cladogram showing common ancestry among some lizards

25. How does evolution happen?
Darwin’s Theory of Natural Selection process by which organisms that are better adapted to their environment survive and reproduce more successfully than less well adapted organisms do Survival of the Fittest

26. Natural Selection theory to explain the mechanism of evolution
There are several factors that Darwin identified that affect the process of natural selection:
Overproduction of offspring
Competition
Variations

27. Overproduction
Most species produce far more offspring than can possibly survive.

28. Competition
Competition is the struggle between organisms for the limited resources in a habitat.

29. Natural Selection: Examples
Are these two butterflies the same species?
Question: Why is the result of this type of natural selection called mimicry?
Answer: Because natural selection results in one species looking like, or mimicking, another species.
These are the Monarch and Viceroy butterflies.
The Monarch on the left is poisonous and the Viceroy is not.
Question: Why would it be beneficial for the Viceroy to look like the Monarch?

30. Natural Selection: Examples
How many moths do you see?

31. Natural Selection: Examples
Checkpoint: A species of hare (rabbit) that is found in a cold tundra environment. How are oversized feet an advantage to the Arctic Hare?
Large feet enable the artic hare to have a better grip on the snow. This adaptation along with coloration, eye size, fur density and color changes enable the artic hare to get away from predators.

32. Who is Charles Darwin? Proposed a way how evolution works
How did creatures change over time?
by natural selection
Collected a lot of evidence to support his ideas
British naturalist
What did Darwin say?
What evidence supports Evolution by Natural Selection?
What impact did Evolution have on biology?

33. Voyage of the HMS Beagle
Invited to travel around the world
(22 years old!)
makes many observations of nature
main mission of the Beagle was to chart South American coastline
After graduation Darwin was recommended to be the conversation companion to Captain Robert FitzRoy, preparing the survey ship Beagle for a voyage around the world.
FitzRoy chose Darwin because of his education, his similar social class, and similar age as the captain.
Darwin noted that the plants and animals of South America were very distinct from those of Europe
Robert Fitzroy

34. Voyage of the HMS Beagle
Stopped in Galapagos Islands
500 miles off coast of Ecuador
The origin of the fauna of the Galapagos, 900 km west of the South American coast, especially puzzled Darwin.
On further study after his voyage, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland.
It seemed that the islands had been colonized by plants and animals from the mainland that had then diversified on the different islands

35. Galapagos
Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland.
800 km west of Ecuador

36. Darwin found…many unique species
Many of Darwin’s observations made him wonder… Why?
Darwin asked:
Why were these creatures found only on the Galapagos Islands?

37. Darwin found…clues in the fossils
present day Armadillos
Darwin found:
Evidence that creatures have changed over time
ancient Armadillo
Darwin asked:
Why should extinct armadillos & modern armadillos be found on same continent?

38. Darwin found… more fossils
present day Sloth
Darwin found:
Evidence that creatures have changed over time
(extinct) Giant ground sloth

39. Darwin found: Different shells on tortoises on different islands
Darwin asked:
Is there a relationship between the environment & what an animal looks like?

40. Darwin found… birds
Darwin found: Many different birds on the Galapagos Islands.
He thought he found very different kinds…
Finch?
Sparrow?
Woodpecker?
Warbler?

41. But Darwin found… a lot of finches
Darwin was amazed to find out: All 14 species of birds were finches…
Darwin asked:
If the Galapagos finches came from the mainland, why are they so different now?
But there is only one species of finch on the mainland!
Large ground finch
Small ground finch
Finch?
Sparrow?
Warbler finch
Tree finch
Woodpecker?
Warbler?

42. The finches cinched it! different beaks are inherited variations
serve as adaptations that help birds compete for food
these birds survive & reproduce
pass on the genes for those more fit beaks
over time nature selected for different species with different beaks
Darwin said:
Ahaaaa! A flock of South American finches were stranded on the Galapagos…
Darwin found: The differences between species of finches were associated with the different food they ate.
Large ground finch
Big seed eater
Small seed eater
Small ground finch
Warbler finch
Insect eater
Tree finch
Leaf & bud eater

43. Relationship between species (beaks) & food

44. Darwin’s finches Darwin’s conclusions variations in beaks
differences in beaks in the original flock
adaptations to foods available on islands
natural selection for most fit
over many generations, the finches were selected for specific beaks & behaviors
offspring inherit successful traits
accumulation of winning traits: both beaks & behaviors
separate into different species

45. From 1 species to 14 species…
Warbler finch
Woodpecker finch
Small insectivorous
tree finch
Large
insectivorous
Vegetarian
Cactus finch
Sharp-beaked finch
Small ground
finch
Medium
ground finch
Large ground
Insect eaters
Bud eater
Seed eaters
Cactus
eater
Warbler
Tree finches
Ground finches
natural selection for best survival & reproduction
variation

46. Earlier ideas on Evolution
LaMarck
evolution by acquired traits
creatures developed traits during their lifetime
give those traits to their offspring
example
in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring
not accepted as valid

47. Darwin’s view of Evolution
giraffes that already have long necks survive better
leave more offspring who inherit their long necks
variation
selection & survival
reproduction & inheritance of more fit traits 

48. Similarities and Differences
Checkpoint: How did Darwin think plants and animals had originally come to the Galapagos Islands?
Answer: Perhaps they had been blown out to sea or set adrift on a fallen log.
Question: What similarities and differences do these two species have? Both species have spines, claws, and scaly skin. Green iguanas are green, have smaller claws, and live in trees. Marine iguanas are gray, have large claws, and live on rocks near the ocean.

49. Darwin’s Theory: REVIEW….
1. Organisms differ; variation is inherited 2. Organisms produce more offspring than survive 3. Organisms compete for resources 4. Organisms with advantages survive to pass those advantages to their children 5. Species alive today are descended with modifications from common ancestors